Temperature control system



B. F. HERR ET AL 2,216,838

TEMPERATURE CONTROL SYSTEM Filed Dec. 50, 1938 Patented oct. s, `1940 Av2,216,838

UNITED STATES PATENT OFFICE 2,216,838 TEMPERATURE CONTROL SYSTEMBenjamin F. Herr and Arthur W. Bassett, Lancaster, Pa., assignors toArmstrong Cork Company, Lancaster, Pa., a corporation of PennsylvaniaApplication December 30, 1938, Serial No. 248,453

7 Claims. (Cl. (i2- 2) This invention relates to an apparatus or systheveining. The veining depends to a large' tem for maintaining asubstantially vconstant extent upon the plasticity or extrudability oftemperature at the surface of a body, the surface the mix and thesecharacteristics are changed by temperature of which must be minutelyconheat-the binder being thermoplastic. As the trolled. heat increasesabove the desired maximum, the 5 The invention nds particular usefulnessin veining becomes longer and more drawn out due linoleum manufacturewhere it is desirable to to greater extrusion and there is a generalblurmaintain a constant temperature at the surface ring or interspersionof the variegating color of the calender rolls and particularly the faceor colors into the base color, resulting in a clouded 10 roll of thesheeting calender employed in the effect upon subsequent operations onthe sheet."10 manufacture of marbleized type striated lino- The sheetprepared as above described is cut leum. In the manufacture of thisproduct, where transversely into strips of a length substantiallyldeviation of the temperature from a predeterequivalent to the width ofthe sheeting calender mined maximum limit has deleterious effects uponand these strips are fed thereto in -a direction at the character of thegraining and where precise right angles to their length or to thedirection 15 control within extremely narrow limits is beneof theveining and cross rolling is eiected to proicial to theproduction of asatisfactory product duce whatis known to the art as cross grainedhaving a uniform graining from edge t edge marble effect. throughout theextent of its length, accurate If the veined sheet be clouded ratherthan temperature control is obviously essential. Addihaving thevariegating colors clearly demarked 20 tionally, in the manufacture ofsuch product, it in the base color, the marble graining will not isdesirable to insure that the graining characbe clearly defined or trulyrepresentative of the teristics of all material manufactured besubgraining characteristics to be reproduced.l stantially the same asthe material made on In the cross rolling operation, temperatureconprevious runs of the same pattern, to guarantee trol is likewise ofparamount importance for upon 25 perfect matching of the product whensubse-v it depends the character of the graining of the quentlyinstalled. nal product, assuming that the veined sheet The commonpractice in marbleized linoleuni originally produced is of the desiredcharacter. manufacture has been to circulate a relatively The usual faceroll temperatures are in the range small volume of brine atarelativelylow temperabetween 25 F. and 45 F. depending upon the 30 ture throughthe calender rolls in ordery to effecparticular mix being operated uponand other tuate the proper heat transfer and thus maintain variableconditions. If the temperature of the a desired temperature at theworking surface surface of the face roll varies'widely from edge of therolls. This has not been satisfactorily to edge, the character of thegraining will likeaccomplished by the apparatus heretofore avail-v wisevary from edge to edge of the sheet along 35 able. The most commondiiculty has been to its length, the graining formed where the roll ismaintain a substantially uniform temperature warmest being excessivelyextruded and having across the face of the roll from edge to edge of agenerally directional, clouded and undesired the workingv surface, itbeing generally fou'nd aspect, whereas the graining formed where the 40that the portion of the face of the roll adjacent roll is at about thedesired temperature will have 40 the zone of introduction ofthe brinewill be mathe requisite characteristics of short, fine but teriallycolder than the zones adjacent the exclearly defined cross graining,characteristic of haust end of the roll, the temperature gradientnatural marble.

progressively increasing from the injector end vThe deficiencies of theprior apparatus are to the exhaustend of the roll surface, in adireccommon and Well known. For example, in the 45 tion parallel to theaxis of the roll. manufacture of some types of linoleum graining,

In the manufacture of marbleized linoleum, the it is desirable tomaintain a face roll temperacomposition in small lumps or masses of baseand ture of about 40 F. and with the prior apparatus variegating coloris first calendered to produce it'was nt uncommon to have a 20 F.temperaa variegated sheet having veining 'running genture diiferential4from end to end vof the roll so 50 erallyA parallel to the length ofthe sheet as it that the roll temperature' in the injector Zone isformed. Since the major constituents of linowould be 40 F. whereas theroll temperature at leum are oxidized oils and fillers and the oil is ofthe exhaust zone would be 60 F. a thermoplastic character, heat above alimited According to our invention, we provide a systemperature willchange the entire character of tem whereby heat transfer fluid, such asbrine, 55

lsurface to be controlled and is recirculated therefrom in a closedcircuit, means being provided for introducing into said closed systemfresh heat transfer fluid, such as brine from a refrlgerating system, ina quantity sumcient to compensate for the temperature change in the heattransfer uid in the closed circuit to thereby maintain a substantiallyuniform temperature in the heat transfer fluid fed to the surface to becontrolled and means are also provided for automatically dischargingfrom the system spent heat transfer fluid in an amount suflicient tocompensate for the fresh heat transfer fluid introduced into the systemto thereby maintain a substantially constant pressure therewithin. Bythis system it is possible to accurately maintain the surfacetemperature of the roll from end to end within minute limits. In actualpractice, 4we have found it possible to maintain the surface temperatureof an eightton calender roll to within 1 F. from end to end of the rollso' that where a 40 F. surface temperature is desirable, we may maintainthe lnjector and at 391/2 F. and the exhaust end at 401/2 F. with theintermediate working zone being maintained at substantially 40 F.

This system is extremely economical to operate since it requires aminimum of fresh heat transfer fluid, the desired effect being attainedby recirculation. within the closed system at a relatively high ow rate,f heat transfer fluid maintained at a temperature closely approachingthe desired roll temperature.

In order that a complete understanding of our invention will befacilitated, We describe the same in conjunction with the attacheddrawing in which:

Figure 1 is a schematic lay-out showing the system of our inventionapplied to a linoleum calender; and

Figure 2 is a detailed view of the rollinjector arrangement and theexhaust and recirculation tubes.

As a typifying example, our system will be described in connection witha linoleum calender, the surface of the face roll at least of which isassumed to require a maintained temperature below normal roomtemperature, say 40 F.`

Referring to Figure 1, there is shown in dotted lines a calendergenerally indicated by the numeral 2 and including a face roll 3 andaback roll I. The surface of the roll 3 is adapted to form the facesurfaceof the linoleumy sheet. the roll 4 forming the rear surface ofthe calendered sheet. As in all calender operations where there ismaterial reduction in thickness of the product from the body fed to thecalender to the product emanating therefrom, there is considerablefrictional heat developed during the calendering operation and thematerial may be relatively warm when it is fed to the calender. 'Ihereis, therefore, an immense heat transfer from the linoleum to the rolland this must be properly controlled to obtain the desired grainingeffect.

Our fluid heat transfer system, which in the.

typical embodiment chosen for illustration is designed for operationwith brine, comprises a fluid pump, including a centrifugal pumping unit5 driven by a motor 6. Heat transfer fluid is forced through a pipe line1 to the injector mechanism of the calender roll l, which mechanism isgenerally indicated by the numeral 8 and is effective for directing theheat transfer fluid into the body of the roll. This injectorlexhaustmechanism per se forms no part of the present invention, but will begenerally described 1 in order that the operation of the system of ourinvention will be clearly understood. 'I'he mechanism is generally shownin Figure 2 and comprises amain casting 9 which is xed and receives an.injector tube III of suitable length for directing the heat transferfluid within the roll body. The, injector tube I0 is adapted to rotatewith the roll 3, and the joint between the injector tube I0 and thecasting 9 is sealed by packing II held in compression by a packing glandI2. Therroll lmay be provided with suitable openings parallel to itsaxis and spaced closely adjacent the peripheral or working surface todirect the cooling fluid as closely adjacent that surfaceas possible.Preferably, the roll is formed as disclosed in the copending applicationof Arlington C. Perry and Benjamin F. Herr, Serial No. 203,952, filedApril 23, 1938, since by the use of such roll the utmost advantages of4the present invention are attained. The present invention is useable,however, with rolls of the typenow commonly employed and other similarrolls. The heat transfer uid after circulation through the roll andabsorption of heat from the linoleum is conveyed through a pipe I3 whichis of' greater diameter than the tube I0 and encircles the same, theheat transfer fluid being discharged into a recirculation line I4forming part of the closed circulatory system as more fully hereinafterdescribed. At the top of the casting 9 there is provided an exhaust tubeI5 for discharge of spent heat transfer fluid. This, likewise, will bemore completely hereinafter described in purpose and function.

YThe recirculation line I4 is connected to a strainer I6 through whichthe reclrculated heat transfer fluid passes prior to its movement to theintake end of the pump 5 through pipe line I1. It will be observed,therefore, that the closed system includes a pump 5 for forcing heattransfer fluid under pressure through pipe line I to the surface of theroll 3 to be vcontrolled and that the heat transfer fluid after passagethrough the ro'll is conveyed by the recirculation line I4 to a strainerI6 and thence by a pipe line I'I to the pump 5 to complete the closedsystem.

One of the problems encountered in maintaining proper temperatures incalendering rolls has been the elimination of loose scale or otherforeign particles from the system. These foreign objects have oftenbecome lodged in the roll openings, thus causing improper circulation ofthe heat transfer fluid, resulting in areas of the roll being materiallywarmer than other 'portions, and the warm areas causing recurringdefects in the graining characteristics. 'nie strainer I8 eliminatesthis problem entirely since.

all foreign objects are removed prior to recirculation of theheattransfer fluid to the pump, and the fluid is thus continuouslyfiltered.

To compensate for the temperature rise in the heat transfer fluid in.the closed system due to heat transfer from the linoleum during thecalenderi'ng operation, we provide means for introducing into the closedsystem a relatively small volume of fresh or unspent heat transferfluid. In the illustrated embodiment. a heat transfer fluid supply lineIl is connected to a source of refrigerated brine, and this is fed bypipe line Il through a. control valve Il to an injector 2| functioningto inject such fresh heat transfer fluid directly into the closedcircuit at a point in advance of the strainer I8 so that such fresh heattransfer fluid is first filtered and mixed with the recirculated heattransfer fluid prior to being pumped to the roll l.

The valve 20 is hand operated but may be thermostatically controlled ifthe particular conditions encountered in use warrant it. For ordinarypurposes on linoleum calenders, a hand controlled valve has been foundsatisfactory; In order to inject such heat transfer fluid into theclosed system, it is essential, of course, to vhave the pressure in thesupply line I8 higher than the pressure in the closed system at theinjector 2I. We have found that a working pressure of 15 pounds in theclosed system and a pressure of 40 pounds in the supply line willoperate with good results.

To compensate for such heat transfer fluid fed to the system and toexhaust therefrom spent heat transfer fluid and avoid the building up ofundue pressure in the system, insuring the maintenance of asubstantially uniform volume of heat transfer fluid therein, we providea pressure relief valve 22 in the return line I5 previously mentioned.This valve 22 is adjusted to v open upon the attainment of apredetermined pressure in the closed system. In the illustratedembodiment a pressure of 15 pounds is desired in the system and,accordingly, the pressure relief valve 22 will be set to release at thatpressure. If fresh heat transfer fluid is continuously fed to the systemthrough the valve 20, then the pressure relief valve 22 will normally beopen in an amount sufficient to permit the exhausting of a comparablequantity of spent heat transfer fluid, thus maintainingauniform'pressure within the closed system. 'Ihe exhaust line I5preferably rises to a point at least as high as the I level of thecirculation tubes in the calender 3 so as to insure that all tubes willbe completely lled with heat transfer fluid at all times. In order toexpel any air which may collect in the system, the pipe line I5 isprovided with a petcock 23 at -its highest point which is opened to ventthe system.

In order that the calender operator may observe the temperature of theheat transfer uid as it is exhausted, a thermometer or other temperatureindicator 24 is provided in the exhaust line I5.

The mode of operation ofour system may be briefly described as'follows:Employing a. typical set of conditions, commonly encountered in linoleummanufacture; it will be assumed that the surface of the calender roll 3is to be maintained at a temperature of 40 F.' In order to effect this,the temperature of the brine as it leaves the pump 5 should be about 9F. and it should be circulated at the rate of about 150 gallons perminute. When the brine leaves the calender roll through the exhaust tubeI4 it will have attained a temperature of about 12 F. In order tocompensate for the rise in temperature of 3 F. from the 9 F. temperatureat the point of injection of the uid to the roll, to the 12l F.temperature at the point of exhaust from the roll, it will be necessaryto inject into the closed system at the rate of about 15 to 20 gallonsp'er minute fresh Vbrine from the supply line I8 which nuid has atemperature of about -20 F. When operating under 15 pounds pressureinthe closed system,

. the pressure relief valve 22 will be set to open If it be desired tothermostatically control the temperature of the heat transfer nuid, athermostat may be placed in the return line I5 for example, in place ofthe thermometer 24, and may be electrically connected with an electricalcontrol valve replacing the hand operated valve 20, the arrangementbeing such that when the temperature in the return line I4 exceeds apredetermined degree the electric valve will be opened and heat transferfluid will be injected into the system to. maintain the desiredtemperature. Such control has not been found necessary with linoleumcalendering. It has been observed that by maintaining a temperaturedifferential of about 28 F. between the desired face roll surfacetemperature and the temperature of the exhaust heat transfer uid thedesired temperature conditions will exist. For example, when it isdesired to maintain a temperature of 40 at the surface of the face roll3 a reading of `2 F. on the thermometer 24 will indicate that atemperature of 40 F. exists at the surface. Our system is, therefore,simple to operate and, since only a relatively small* volume of freshheat transfer fluid is introduced to the system, operating economies areeffected. Our system oper` ates on the principle of' recirculatingheattransfer fluid at a temperature closely approaching the desired surfacetemperature at a relatively high rate of flow and adding to such fluidin circulation a relatively small increment of fresh heat transfer fluidto maintain a uniform temperature in the mixture fed to the surface tobe controlled.

While we have described and illustrated certain preferred embodiments ofour invention, it will be' understood that the invention may beotherwise embodiedand practiced within the scope of the followingclaims.

We claim:

l. In a system for the control of temperature at the working surface' ofa body, a source of pressure supply of unspent heat transfer fluid, asubstantially closed system for the circulation of heat transfer fluidunder pressure, including a fluid pump, means for conveying heattransfer fluid fromsaid pump to the surface to be controlled, and meansfor recirculating said fluid from said surface back to said pump, apressure relief valve for maintaining the pressure of said fluid in saidcirculating system substantially constant, and means for introducingunspent heat transfer fluid from said source of pressure supply intosaid circulating system.

2. In a system for the control of temperature at the working surface ofa body, a source of supply of unspent heat transfer fluid, asubstantially closed system for the circulation of heat transfer fluidunder pressure, including a fluid pump, means for conveying heattransfer fluid from said pump to the surface to be controlled, and meansfor recirculating said fluid from said surfacek back to said pump, meansfor continuously filtering said heat transfer fluid in said system, apressure relief valve for maintaining the pressure in said systemsubstantially constant,

, at the working means for continuously introducing unspent heattransfer fluid from said source of supply into said circulating system,and means for discharging spent heat transfer fluid from saidcirculating system through said pressure relief valve.

3. In a system for the control of temperature at the working surface ofa rotating body, a source of pressure supply of unspent heat transferfluid, a substantially closed system for continuously circulating heattransfer fluid under pressure, including a fluid pump, means forconveying heat transfer fluid from said pump to the surface to becontrolled, and means for recirculating said fluid from said surfaceback to said pump, means for continuously filtering said heat transferfluid in said system, means for the discharge of heat transfer fluidfrom said recirculating system, said last named means including a fluidconveying member disposed at an elevation at least as high as the levelof heat transfer fluid to be maintained in said rotating body, apressure relief valve in said means for the discharge `of heat transferfluid for maintaining a constant pressure within the system less thanthe pressure of said source of pressure supply of unspent heat transferfluid, means for introducing unspent heat transfer fluid from saidsource of pressure supply into said circulating system, and means forcontrolling the ow of said unspent heat transfer fluid into said system.

4. In a system for the control of temperature surface of a body, asource of pressure supply of unspent refrigerated heat absorbing fluid,a substantially closed system for the circulation of refrigerated, heatabsorbing fluid under pressure, including a fluid pump, means forconveying said refrigerated heat absorbing fluid from said pump to thesurface to be controlled, means for recirculating said refrigerated heatabsorbing fluid from said surface back to said pump, an adjustablepressure relief valve for maintaining a substantially constant pressureof refrigerated heat absorbing fluid in said circulating system, andmeans for introducing said unspent refrigerated heat absorbing fluidfrom said source of pressure supply into said circulating system.

5. In a system for the control of temperature at the working surface ofa rotating body, Ia source of supply of unspent heat transfer uid, asubstantially closed system for continuously circulating heat transferfluid under pressure, including a fluid pump, means for conveying heattransfer fluid from the pump to the surface to be controlled, and meansfor recirculating said fluid from said surface back to said pump, a

sure therewithin, and means for introducing unspent heat transfer fluidfrom said source of supply into said circulating system.

6. In a method of maintaining a substantially uniform temperature at theworking surface of a calender roll, the steps consisting in continuouslycirculating refrigerated brine under pressure to said calender roll andrecirculating such brine therefrom in a substantially closed circuit andunder predetermined pressure, continuously injecting into Asaid circuitunspent refrigerated brine at a temperature substantially lower than thetemperature of the brine in circulation, mixing the unspent brine withthe brine in circulation and filtering the resultant mixture prior topresenting the same to the calender roll, and discharging spent brinefrom said circuit upon the attainment of a predetermined pressuretherein.

7. In a method of maintaining a substantially uniform temperature at theworking surface of a calender roll, the stepsy consisting incontinuously circulating refrigerant under pressure to said calenderroll and recirculating such refrigerant therefrom in a substantiallyclosed circuit under predetermined pressure, at a temperature closelyapproaching the. desired temperature at the working surface of thecalender roll, and at a relatively high rate of flow, injecting intosaid circuit a relatively small increment of unspent refrigerant at atemperature substantially lower than the temperature of the refrigerantin circulation, mixing the unspent refrigerant with the refrigerant incirculation, and discharging spent refrigerant from said circuit on theattainment of a predetermined pressure therein.

BENJAMIN F. HERR. ARTHUR W. BASSETT.

